Ya don need a Bosendorfer?

[Tvak@aol.com]

In a message dated 5/15/03 5:03:11 PM, Richard.Brekne@grieg.uib.no writes:

>I believe the phenomena is called difference tones

Supposedly Mozart was aware of this phenomenon and used it in his 
compositions to fill out the sound in certain circumstances.  

In college theory class we were exposed to difference tones, but high pitched 
sine tones were used.  Odd intervals like a major second or a perfect fourth 
could produce a very audible lower tone a couple of octaves down.  This note 
was predictable but I can't remember how they were determined.  I do remember 
hearing a series of high pitched intervals that clearly resulted in a low C 
major scale.  It was really entertaining.  (For a theory class.)

Think of that Emergency Broadcast System test tone on the radio ("THIS IS 
ONLY A TEST!!  IF IT WERE A REAL EMERGENCY...).  That used to be a major 
second, A4 and B4, and you could hear the difference tone if the TV was 
cranked loud enough.  (I say 'used to be' because the last time I heard the 
Emergency Broadcast announcement, it was a modem tone.)

I could imagine that a woodwind quintet might produce difference tones on 
certain chords that could be audible, but the idea of playing two piano notes 
to produce a lower tonewould be, in my opinion, impossible.  (I have no 
scientific reasons to back this up, though.)

Tom Sivak